Technical Field
The present disclosure relates to a crimp terminal for electrical connection with other components, a connecting structure using the crimp terminal, a method of manufacturing the crimp terminal and a laser welding method of the crimp terminal.
Background
In the field of vehicles, in view of improving fuel consumption, there is a need for lightweighting of various components constituting automobiles. Particularly, a wire harness used in automobiles is a component having a considerable weight in an automobile and thus, for lightweighting, there have been efforts to change a material of a conductor (core wire) of an electric wire used in the wire harness from copper to one of aluminum and an aluminum alloy. Normally, a crimp terminal made of one of copper and a copper alloy is used for a terminal connected to a leading end portion of an aluminum or aluminum alloy wire. Accordingly, since there is a possibility that exposed aluminum produces dissimilar metal corrosion and the conductor becomes defective at a connecting portion between the conductor and the terminal that are made of the aforementioned materials, it is necessary to take measures such as to shield the aluminum conductor from the outside world.
To this end, it is known to mold an entire crimp portion with a resin (e.g., see Japanese Laid-Open Patent Publication No. 2011-222243). However, this results in a bulky connector since the size of a connector housing needs to be larger because of a bulky mold portion, and thus a wire harness as a whole cannot be miniaturized or have a higher density. With a molding method, since individual crimp portion is processed after the crimping of an electric wire, there is a problem that manufacturing processes of a wire harness may largely increase or become cumbersome.
In order to solve such a problem, there are proposed techniques such as a technique in which a metal cap is placed to cover the electric wire conductor and thereafter crimped to thereby bring an aluminum conductor into a sealed state and a technique in which a crimp terminal and a metal cap are not provided as separate components but rather an electric wire is covered with a part of a strip of terminal to provide a sealed state (e.g., see Japanese Laid-Open Patent Publication Nos. 2004-207172 and 2012-84471, and International Publication WO2014/010605).
Here, an electric wire including an aluminum conductor is crimped in a covered state, a method in which a part of a substrate (metal plate) stamped to correspond to a shape of the crimp terminal is bent into a cylindrical shape, and a butted portion or a lapped portion at both ends thereof is welded by a laser provides both improved formability and productivity.
However, when laser welding the overlapped portion to make an electric wire into a sealed state, there is a possibility that a keyhole 101 could be formed at the end of welding as shown in FIG. 10. As a result, there was a drawback that the welding of the overlapped portion 102 may become incomplete, and a possibility that an electric wire cannot be sealed increases.
Accordingly, the present disclosure is related to providing a crimp terminal that can accurately perform the welding of the overlapped portion without lowering the quality of the crimp terminal, a connecting structure using the crimp terminal, a method of manufacturing the crimp terminal and a laser welding method of the crimp terminal.